Pain
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Editorial Comment Review
Is intranasal ketamine an appropriate treatment for chronic non-cancer breakthrough pain?
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The SF-36 is a well-validated health status instrument measuring eight different health concepts. One aim of this study was to compare health status as measured by SF-36 in subjects from the general population with no chronic pain (NCP), chronic regional pain (CRP), and chronic widespread pain (CWP). A second aim was to assess if SF-36 could reflect changes in pain status over time. ⋯ Changes in SF-36 over the 3-year follow up time coincided with improvement or deterioration of pain status. Baseline SF-36 scores predicted pain outcome 3 years later. These results support that both physical and mental aspects of health status as measured by SF-36 are affected by the burden of musculoskeletal pain, are sensitive to changes in pain status, and also predict the further development of pain.
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Clinical Trial
Lowering fear-avoidance and enhancing function through exposure in vivo. A multiple baseline study across six patients with back pain.
This study investigated the effects of an exposure in vivo treatment for chronic pain patients with high levels of fear and avoidance. The fear-avoidance model offers an enticing explanation of why some back pain patients develop persistent disability, stressing the role of catastrophic interpretations; largely fueled by beliefs and expectations that activity will cause injury and will worsen the pain problem. Recently, an exposure in vivo treatment was developed that aims to enhance function by directly addressing these fears and expectations. ⋯ These improvements were observed even though rated pain intensity actually decreased somewhat. Thus, the results replicate and extend the findings of previous studies to a new setting, with other therapists and a new research design. These results, together with the initial studies, provide a basis for pursuing and further developing the exposure technique and to test it in group designs with larger samples.
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Intrathecal administration of serotonin type 2 (5-HT(2)) receptor agonists, alpha-methyl-5-hydroxytryptamine maleate (alpha-m-5-HT) or (+/-)-1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI), produces antiallodynic effects in a rat model of neuropathic pain. In the present study, we examined the antiallodynic effects of intrathecally administered agents which are selective for 5-HT(2C) receptors. Allodynia was produced by tight ligation of the left L5 and L6 spinal nerves, and was measured by applying von Frey filaments to the left hindpaw. ⋯ The preferential 5-HT(2A) receptor antagonist ketanserin (30 microg) did not reverse the effects. In contrast to 5-HT(2C) receptor agonists, the antiallodynic effects of intrathecally administered alpha-m-5-HT (30 microg) and DOI (100 microg) were reversed by ketanserin, but not by RS-102221. These results indicate that 5-HT(2C) receptors have a role in spinal inhibition of neuropathic pain, and the effects produced by intrathecal administration of 5-HT(2C) receptor agonists are mediated by a mechanism different from that of alpha-m-5-HT or DOI, which seem to produce their effects through 5-HT(2A) receptors.
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The 'nociceptive' blink reflex is a method of examining human trigeminal pain pathways. We explored temporal summation of this reflex by using a train of pulses, rather than a single pulse, and remote activation of diffuse noxious inhibitory control (DNIC), to improve reliability, flexibility and nociceptive specificity of this technique. The R2 component of the nociceptive blink reflex response (nR2) was assessed in 28 healthy volunteers using between 1 and 7 pulses per stimulus train (inter-pulse interval 5 ms). ⋯ Activation of the DNIC system using heterotopic pain suppressed the nR2 evoked by double and triple stimulation by 16 and 42%, respectively, but not the nR2 from a single pulse. Stimulation with double and triple pulses may be more suitable to study influences on nociceptive pathways than single pulses and may widen the methodological flexibility of the nociceptive blink reflex technique. This technique may be useful in studying the trigeminal nociceptive system with particular reference to primary headache disorders and their neuropharmacology.